September 9, 2011 - Warren Held
Windows 8 Fast Boot
Now here’s the key difference for Windows 8: as in Windows 7, we close the user sessions, but instead of closing the kernel session, we hibernate it. Compared to a full hibernate, which includes a lot of memory pages in use by apps, session 0 hibernation data is much smaller, which takes substantially less time to write to disk.
There is a graph below that shows Microsoft’s comparison of boot times between Windows 7 and Windows 8 across 30 different PCs. Below that is a video demonstrating a super fast boot of Windows 8 on a laptop (I think it is running a SSD, and not a regular hard drive, because it instantly boots).
Source and for a much more in-depth look at Windows 8 boot: https://blogs.msdn.com/b/b8/archive/2011/09/08/delivering-fast-boot-times-in-windows-8.aspx